Switching to Leaflet¶

Leaflet is one of the most popular web mapping libraries. In this exercise we take the drawing app you built in the exercises and migrate it from MapLibre GL JS to Leaflet — and you will see that the Terra Draw code does not change at all.

The starting point: MapLibre¶

This is the app we are migrating. Unlike the earlier exercises, the code below also creates the map — because that is exactly the part that differs between libraries. The library-specific parts are marked with comments.

What changes¶

To use Terra Draw locally with Leaflet, install Leaflet and its adapter:

pnpm install -D leaflet @types/leaflet terra-draw-leaflet-adapter

Only three things change. Everything else — modes, styles, events, data management, the UI buttons — stays exactly the same.

1. Imports¶

-import { Map as MapLibreMap } from 'maplibre-gl';
-import { TerraDrawMapLibreGLAdapter } from 'terra-draw-maplibre-gl-adapter';
+import L from 'leaflet';
+import { TerraDrawLeafletAdapter } from 'terra-draw-leaflet-adapter';

(In a local project you also swap the CSS import: maplibre-gl/dist/maplibre-gl.css → leaflet/dist/leaflet.css. The live editor loads the CSS for you.)

2. Map creation¶

-const map = new MapLibreMap({
-    container: 'map',
-    style: 'https://tiles.openfreemap.org/styles/bright',
-    center: [132.4553, 34.3966],
-    zoom: 12
-});
+const map = L.map('map').setView([34.3966, 132.4553], 12);
+L.tileLayer('https://tile.openstreetmap.org/{z}/{x}/{y}.png', {
+    maxZoom: 19,
+    attribution: '&copy; <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a>'
+}).addTo(map);

Coordinate order

MapLibre uses [lng, lat] while Leaflet uses [lat, lng]. This is the most common mistake when switching between the two.

3. The adapter — and when to start¶

 const draw = new TerraDraw({
-    adapter: new TerraDrawMapLibreGLAdapter({ map }),
+    adapter: new TerraDrawLeafletAdapter({ map, lib: L }),
     modes: [ /* unchanged! */ ]
 });

-map.once('load', () => {
-    draw.start();
-});
+// Leaflet is ready synchronously — no `load` event to wait for.
+draw.start();

The result: Leaflet¶

Here is the same app after applying the three changes above — now running on Leaflet. Compare it with the MapLibre version at the top of the page: the Terra Draw part is byte-for-byte identical. Edit the code and press Run ▶ to experiment.

TypeScript with Leaflet v1 + SvelteKit

In a local SvelteKit project, Leaflet v1 may raise a TypeScript error by default. If so, change module and moduleResolution to nodenext in tsconfig.json.

What's Next?¶

The same three-step recipe works for every other library. Next: OpenLayers.